Frying is an ancient cooking operation wherein the food to be cooked is placed in contact with a cooking oil which is heated to a relatively high temperature. The amount of cooking oil varies from a small amount in sauteing or pan-frying to enough to cover the food in deep fat frying. The cooking temperature is not limited by the boiling point but by the smoking temperature of the oil, that is the temperature at which the oil decomposes and fumes become visible. Because the decomposition is irreversible and reduces the usefulness of the oil, heating an oil to its smoking point is to be avoided. Temperatures of from 350.degree. to 390.degree. F. are generally employed in deep fat frying. Animal or vegetable oils are generally used as the frying medium, for example corn oil has a high smoke point so that it can withstand high frying temperatures up to 440.degree. F. without smoking or burning.
Deep fat fryers are made of cast iron, sheet steel, stainless steel or aluminum, and are provided with a wire immersion basket for holding and draining food.
The best frying temperature is about 375.degree. F., which is suitable for frying meats, fish, vegetables and pastries. The deep fat fryer is filled one-third full with the cooking oil and brought to the desired cooking temperature. Fresh or frozen food to be fried is then inserted into the basket and the basket immersed into the hot oil. At initial contact of the food with the hot oil, any water or ice in contact with the food is instantly vaporized and forms small pockets of steam which expand with an almost explosive force. The steam propels small droplets of the hot cooking oil out of the oil reservoir and splatters them on all surrounding surfaces including the cook and the kitchen. Not only does this pose a cleaning problem but, more importantly, it poses a primary hazard of scalding or burning the cook by direct contact with the hot oil and poses a secondary hazard of creating an air sol of oil droplets which is inflammable and may catch fire if exposed to an open flame. The prudent cook will attempt to cover the deep fat fryer to reduce oil splattering, but heretofor this has only been possible after the basket has reached the bottom of the hot oil reservoir.